Subcarinal Lymph Node Importance Revisited

Abstract

Eckardt and colleagues [1Eckardt J. Jakobsen E. Licht P.B. Subcarinal lymph nodes should be dissected in all lobectomies for non-small cell lung cancer—regardless of primary tumor location.Ann Thorac Surg. 2017; 103: 1121-1125Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar] reviewed from a national registry 5,577 patients with clinical N0 non-small cell lung cancer (NSCLC) who underwent operation with mediastinal lymph node (LN) dissection. Unsuspected N2 disease was discovered in 612 (11.0%) patients; 193 (3.5%) patients had subcarinal metastasis (station 7). Subcarinal N2 disease was significantly more common in patients with lower-lobe or middle-lobe cancers than in those with upper-lobe cancers (5.8% vs 1.6%, p < 0.01). Subcarinal pN2 being possible despite negative preoperative invasive mediastinal staging, they advocated station 7 routine lymph node (LN) dissection or sampling whatever the lobe of the NSCLC to avoid understaging. We have already suggested this conclusion [2Riquet M. Rivera C. Pricopi C. et al.Is the lymphatic drainage of lung cancer lobe-specific? A surgical appraisal.Eur J Cardiothorac Surg. 2015; 47: 543-549Crossref PubMed Scopus (66) Google Scholar]. However, it is of prime importance to recall in addition the potential underlying significance of subcarinal LN tumoral involvement. We observed in a surgical series [2Riquet M. Rivera C. Pricopi C. et al.Is the lymphatic drainage of lung cancer lobe-specific? A surgical appraisal.Eur J Cardiothorac Surg. 2015; 47: 543-549Crossref PubMed Scopus (66) Google Scholar] that pN2 involvement concomitantly existed in the upper and lower mediastinum in 40% to 81% of patients according to the side and location within the lobe of NSCLC; the lower mediastinum mainly consisted in subcarinal N2. Multistation N2 involvement is known to worsen the prognosis. Furthermore, in an anatomic study wherein the subpleural lymphatics of 300 lung segments were injected in 200 adults [3Riquet M. Hidden G. Debesse B. [Intertracheobronchial lymph nodes: lymph inflow and outflow in lung segments from 200 adult subjects].Bull Assoc Anat (Nancy). 1986; 70: 43-48Google Scholar], subcarinal LNs were reached by the lymph of three segments out of five. It was injected in 25% of the upper lobes and in 90% to 100% of the lower lobes, both from the right lungs and from the left lungs. In almost one third of cases, the injection remained in the LNs without further progressing. In the other cases, the injection continued to the LN stations of the upper right and left mediastinum: stations 4R, 3, and 4L in particular. In one third of cases, only one of these stations was involved. In the other cases, the injection continued in two, occasionally three, LN stations. If these results are analyzed with respect to the side of the injected pulmonary segment, contralateral lymphatic drainage was observed from both the left lung and the right lung through these subcarinal LNs. Thus, it is mandatory to resect these LNs in upper lobe cancers, but it is also important to remember their prognostic implication whatever the side and the lobe, upper or lower, in tumoral lymphatic dissemination to the superior mediastinum, both ipsilateral and contralateral. Subcarinal Lymph Nodes Should be Dissected in All Lobectomies for Non-Small Cell Lung Cancer—Regardless of Primary Tumor LocationThe Annals of Thoracic SurgeryVol. 103Issue 4PreviewMediastinal staging is of paramount importance for planning of treatment in non-small cell lung cancer (NSCLC). Single institution reports recently claimed that subcarinal lymph node dissection during resection of upper lobe NSCLC could be spared. We used a complete national lung cancer registry to investigate patterns of unsuspected mediastinal lymph node involvement after lobectomy. Full-Text PDF ReplyThe Annals of Thoracic SurgeryVol. 105Issue 2PreviewWe thank Riquet and colleagues [1] for their interest in our study [2] and their valuable comments. In our article we cited their important work and fully agree with the point they raise that subcarinal lymph nodes should be dissected or sampled routinely during all surgical procedures for non-small cell lung cancer (NSCLC) to avoid understaging—regardless of the results of preoperative invasive mediastinal staging and tumor location. In addition, Riquet and colleagues [1] bring attention to some of their early work on specific mediastinal lymphatic drainage patterns, which is important because they demonstrated that subcarinal nodes play a key role for further lymphatic spread, both ipsilaterally and contralaterally. Full-Text PDF